DAY 1

DataStructures/02-Python/01-LinkedLists/01-single_linked_list.py

@@ -0,0 +1,106 @@
+class Node:
+    """
+    A base class for single linked list.
+    """
+    def __init__(self, info, link=None):
+        self.info = info
+        self.link = link
+
+
+class SingleLinkedList:
+    """
+        An implementation of single linked list.
+            1. Insert
+            2. Delete
+            3. Traverse
+    """
+    def __init__(self):
+        self.head= None
+
+    def insert_at_begin(self, info):
+        """
+            Method to insert Node into a linked list at first.
+        """
+        new_node = Node(info)
+        if self.head != None:
+            new_node.link =self.head
+            self.head = new_node
+        else:
+            self.head = new_node
+
+    def insert_at_end(self, info):
+        """
+            Method to inser Node into a linked list at end.
+        """
+        new_node = Node(info)
+        if self.head != None:
+            current = self.head
+            while current.link != None:
+                current = current.link
+            current.link = new_node
+        else:
+            self.head = new_node
+
+    def delete_node(self, ele):
+        """
+        ---------->
+        2 -> 5 -> 10
+        """
+        # CASE 1: When List is empty
+        if self.head == None:
+            print("List is empty")
+            return
+
+        # CASE 2: When List is First Element
+        if self.head.info == ele:
+            temp = self.head
+            self.head = temp.link
+            temp = None
+            return
+        # CASE 3: When element is at last and in between
+        current = self.head
+        while current.link != None:
+            if current.link.info == ele:
+                temp = current.link
+                current.link = temp.link
+                temp = None
+            current = current.link
+        print("DELETION NOT POSSIBLE")
+
+    def display(self):
+        # CASE 1: List is empty
+        if self.head == None:
+            print("List is empty.")
+            return
+        current = self.head
+        while current != None:
+            print(current.info)
+            current = current.link
+
+    def search(self, ele):
+        if self.head == None:
+            print("List is empty.")
+            return
+
+        current = self.head
+        while current != None:
+            if current.info == ele:
+                print("Eelement is found in list)
+                return
+            current = current.link
+        print("LIST NOT FOUND")
+
+
+if __name__ == "__main__":
+    LL = LinkedList()
+    LL.insert_at_begining(10)
+    LL.insert_at_begining(5)
+    LL.display()
+    print("*******")
+    LL.insert_at_end(20)
+    LL.insert_at_end(30)
+    LL.display()
+    LL.delete_node(40)
+    LL.delete_node(20)
+    LL.display()
+    LL.search(30)